Apparatus for removably inserting an electronic tire tag into a tire

ABSTRACT

An improved method and apparatus permits the insertion and removal of an electronic monitoring device from a tire, while securing the electronic monitoring device to the tire so that stress, strain, impact, cyclic fatigue and vibration are minimized. After a rubber patch is vulcanized, the patch is permanently assembled to the innerliner of a vulcanized tire by affixing it to the tire innerliner. An electronic monitoring device, after having been encapsulated in a suitable rigid potting material to form a rigid tag, is fitted with a power source to form a tag assembly in a shape which allows for insertion into a cavity in the patch. The tag is carefully inserted into the cavity housing. The tag assembly is locked into place within the cavity using a suitable removable locking device.

This application is a continuation application of application Ser. No.09/021,518, now U.S. Pat. No. 6,530,478, filed Feb. 10, 1998.

FIELD OF THE INVENTION

This invention pertains to an apparatus and a method of inserting andremoving an active tag into a compartment which is permanently attachedto a tire. More particularly, this invention sets forth a method andapparatus for inserting and removing an electronic device encapsulatingin a rigid material, into a compartment of a vulcanized rubber patchwhich is permanently attached to a vulcanized tire.

BACKGROUND OF THE INVENTION

It is desirable to monitor engineering conditions of tires, such aswear, internal pressure and internal temperature in order to reduce tirecosts and maximize vehicle efficiency. Of course, it is advantageous toperform such monitoring in large truck tires, which are expensive.

Prior art methods of monitoring large truck tires have included passiveintegrated circuits embedded in the body of the tire, or self-poweredcircuits which are positioned external to the tire. The passiveintegrated circuits rely on inductive magnetic coupling or capacitativecoupling to energize the circuit, thus providing power to the circuitfrom a source remote from the tire. Self-powered circuits positionedexternal to the tire are exposed to damage from the environment such asweather, road hazards and even vandalism.

Recent engineering advances have permitted the installation ofmonitoring devices having active integrated circuits within tires. Onesuch device is described in U.S. Pat. No. 5,562,787 to Koch et al.entitled “Method of Monitoring Conditions of Vehicle Tires”,incorporated herein by reference, and assigned to the assignee of thepresent invention. These devices include an active circuit powered by adedicated long life, miniature battery and at least one senor fordetecting, optionally storing and transmitting real time engineeringconditions within the tire. Such devices are capable of being programmedto remain in an active, but dormant condition, but will switchautomatically to an “awakened” condition in response to an externalsignal or a condition which exceeds preset limits.

One of the problems faced with such active devices is that they aredelicate electronic devices that must operate in the harsh environmentof a tire. Thus it is important to secure these devices in the tires tominimize the effect of the harsh tire environment on them, while stillpermitting them to be exposed to this environment to allow accuratemonitoring of the engineering conditions for the life of the tire. Theseactive devices have previously been mounted in tires by firstencapsulating the device or power-containing circuit in a material whichforms a rigid or semi-rigid encasement about the device, therebyinhibiting straining of the device as a result of applied stressesduring operation. Such materials have included non-foam compounds suchas urethanes, epoxies, polyester-styrene resins, hard rubbercompositions, and the like. The encapsulated device is then placed intoa green rubber material which forms a housing or is placed in a greenrubber pocket or pouch that becomes part of the tire. The encapsulateddevice is then permanently set within the rubber material during asubsequent vulcanizing operation. The encapsulated device, including thepower source or battery, is then permanently assembled to the tire, sothere is no way to replace the battery once it is discharged, nor isthere a practical way to disassemble the encapsulated device to repair afailed component.

While the methods and apparatus of U.S. Pat. No. 5,562,787 provide anacceptable method of assembling an active chip into a tire cavity, animproved method and apparatus which permits assembly and disassembly ofthe encapsulated device and battery from the tire.

SUMMARY OF THE INVENTION

In accordance with the present invention, an improved method andapparatus for assembling and disassembling an active electronicmonitoring device into a tire is disclosed.

The improved method and apparatus permits the insertion and removal ofan electronic monitoring device from a tire, while securing theelectronic monitoring device to the tire so that stress, strain, impact,cyclic fatigue and vibration are minimized. A rubber patch having afirst side which includes a housing with a cavity having a preselectedconfiguration and a second opposite side approximating the contour of aninnerliner of a fire is prepared. Although the rubber patch may beassembled to the tire and vulcanized with the tire, it is much morepractical to assemble the rubber patch to the tire after both the rubberpatch and the tire have been vulcanized. After the rubber patch isvulcanized, the patch is permanently assembled to the innerliner of avulcanized tire by affixing the second opposite side of the patch to thetire innerliner. The electronic monitoring device, after having beenencapsulated in a suitable rigid potting material to form a rigid tag,is fitted with a power source to form a tag assembly in a shape whichallows for insertion into the contour of the cavity housing which iscarefully inserted into the cavity housing. The tag assembly is lockedinto place within the cavity using a suitable removable locking means.

An advantage of the present invention is that the tag assembly may beinserted into the tire after vulcanization of the tire and after theassembly of the patch to the tire. Because the tag assembly is lockedinto place using removable locking means, the tag assembly may beremoved at any time during the life of the tire to replace the rigid tagor the power source. Thus, if a battery fails, it may be easily replacedso that the tag assembly can continue to operate. If the rigid tag failsbecause of a failure of any of the components comprising the tag, it caneasily be removed or replaced.

Another advantage of the present invention is that is a tire is to beretreaded, the tag assembly may be removed from the tire during thevulcanizing operation and replaced after completion of the vulcanizingoperation, so that the sensitive and delicate electronic circuitry ofthe rigid tag and the batter are not subjected to the harsh environmentof the vulcanizing operation, which could destroy or adversely affectits life.

Since the tag assembly is removable for repair or replacement, a furtheradvantage is that, in the event of a failure of the battery or anycomponent of the rigid tag, it is not necessary to assemble a secondpatch assembly to the tire.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification. The invention itself, however, both as to itsorganization and its method of practice, together with further objectsand advantages thereof, may best be understood by the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a cross-sectional view of the rubber patch of the presentinvention showing the housing and cavity for the tag assembly;

FIG. 2 is a cross-sectional view of the rubber patch of the presentinvention attached to the innerliner of a tire;

FIG. 3 is a cross sectional view of-the electronic monitoring deviceembedded in potting material;

FIG. 4 is a cross-sectional view of the mold used to embed theelectronic monitoring device in the potting material;

FIG. 5 is a cross sectional view showing a battery attached to the tag;forming a tag assembly;

FIG. 6 is a cross-sectional view of the tag assembly assembled insidethe cavity of the tire patch, with a locking device holding the tagassembly in place, before crimping of the locking device;

FIG. 7 is a second embodiment of the present invention depicting across-sectional view of the tag assembly being locked inside the cavityof the tire patch with a threaded insert;

FIG. 8 is a third embodiment of the present invention showing a threadedtag assembly threaded into the cavity of the rubber patch housing; and

FIG. 9 is a fourth embodiment of the present invention, shown inperspective, showing a slot and tab arrangement for locking a tagassembly to a rubber patch housing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

FIG. 1 shows a rubber patch 10 of the present invention. The patch 10has a first side 12 which includes a housing 14 with a cavity 16 of apreselected configuration. As shown in FIG. 1, the housing 14 has acavity 16 which is cylindrical, although the cavity 16 may be of anyconvenient configuration, as will become apparent from the descriptionwhich follows. The patch has a second opposite side 18 approximating thecontour of an innerliner of a tire (not shown). In a preferredembodiment, the rubber patch is vulcanized and then assembled to thevulcanized tire. Although any method for assembling the vulcanizedrubber patch to the vulcanized tire, one acceptable and preferred methodis set forth in U.S. Pat. No. 5,971,046; the disclosures of which areincorporated herein by reference. In accordance with the referencedapplication, the patch may be a rubber selected from the groupconsisting of Ethylene Propylene Diene Monomer (EPDM) rubber, butylrubber, natural rubber, neoprene and mixtures thereof. One preferredembodiment is a mixture of chlorobutyl rubber and natural rubber.Another preferred embodiment is a mixture of Styrene-Butadiene rubber(SBR) and natural rubber. Typically, patches made of these rubbercompositions may be cured by heating to a temperature of about 150° C.and holding at this temperature for about 30 minutes. The time andtemperature may be modified as necessary to achieve sufficient curing ofthe patch for further assembly. The second side of the patch 18approximates the contour of an innerliner of a tire. The contour of thesecond side 18 preferably is radiused to have about the same radius asthe tire to which it is assembled, the radius being larger for largertires. For very large tires, such as for off-the-road tires, the radiusmay be eliminated altogether, so that there is no contour and theopposite side is flat, having no contour.

Affixed to the second side 18 of the vulcanized tire patch is a dualcure bonding layer 20, which has a first side (not shown) and a secondside 22. This dual cure bonding layer may be assembled to the patch atany time following vulcanization of the patch and prior to assembly ofthe patch assembly to the tire innerliner. The dual cure bonding layeris permanently assembled to the patch to form patch assembly 60. Anon-curing cement (not shown) is applied to side 18 of the patch inorder to hold the dual cure bonding layer 20 onto the patch. Thenon-curing cement and the dual cure bonding layer are products of PatchRubber Company. The important feature of the dual cure bonding layer isthat it can be chemically activated and cured, without the need forheating to an elevated temperature. The process is diffusion controlled,however, and some minimal heating will speed the curing process. Thedual cure bonding layer may be any material which can be activated andcured to the vulcanized rubber of the tire innerliner and the vulcanizedpatch. Preferably, however, the dual cure bonding rubber is naturalrubber. The dual cure bonding rubber, after application of theactivating cement, may cure at room temperature over a period ofseventy-two (72) hours. However, if more rapid curing is desired, thismay be accomplished by heating to 45° C. for at least twenty-four hours.

Referring now to FIG. 2, patch assembly 60 is then assembled to theinnerliner 75 of tire 71. Activating cement is first applied to secondside 22 of dual cure bonding layer 20. The patch assembly is thenstitched to the innerliner of the vulcanized tire and the patchassembly/tire assembly is allowed to cure for a sufficient time andtemperature to form a strong bond between the tire and the patchassembly. The times and temperatures utilized for this curing may bebasically the same times and temperatures as previously discussed. Toensure a strong bond, the patch assembly optionally may be clamped tothe tire innerliner 75, until the curing cycle is completed.

The electronic monitoring device is a circuit board which includessensors and optional an antenna. The electronic monitoring device mayinclude a power source or battery, although the battery may be attachedto the electronic monitoring device at a later time. In the preferredembodiment, the battery is not included as part of the electronicmonitoring device. The electronic monitoring device 34 is encapsulatedin a potting material 40 which solidifies into a rigid material as shownin FIG. 3. Referring to FIGS. 3 and 4, the electronic monitoring device34 is placed within a mold 40 having a first half 52 and a second half54. The mold is then filled with the potting material 40 in fluid form,which fills the mold and flows around the electronic monitoring deviceand allowed to cure, resulting in a rigid tag. Any potting materialhaving a Young's Modulus of at least 30,000 psi and which is capable ofbeing molded around the electronic monitoring device without damagingany of the components of the device. Preferably, the potting materialhas a Young's Modulus of at least about 100,000 psi. Two preferredpotting materials include epoxy and urethane. If desired, the curing ofthe potting material around the electronic device may be accelerated bypreheating the mold to an elevated temperature which is above ambient,but below the temperature at which damage to the electronic monitoringdevice will occur. A preferred temperature is about 80° C. After theepoxy has been cured, the mold halves 52, 54 are separated, yielding arigid, encapsulated tag 30. In a preferred embodiment, FIG. 5, a battery68 which provides power to the tag 30 is attached to the tag to form atag assembly 70. Although the battery is shown as held in positioncontacting the electronic monitoring device 34 by threading, anysuitable means of attaching the battery to the circuit board so that thebattery may be removed is acceptable. Alternate means of attaching thebattery to the circuit board may include spring clips, lock pins orother hold down devices.

The tag assembly 70 may be of any configuration which allows it to fitwithin the contour of the cavity 16, both of which are cylindrical inthe embodiment shown in FIG. 1. In the preferred embodiment, tagassembly 70 is assembled into the cavity 16 as shown in FIG. 6. Sincethe rubber patch assembly can be attached to the tire using an air cureor low temperature cure, it is understood that the sequence ofassembling the tag assembly into the rubber patch housing may beaccomplished either before or after the rubber patch is attached to thetire innerliner. Tag assembly includes an optional antenna 72. Housing14 includes slots 74 to receive the antenna. After the tag assembly 70is in place within the cavity, at least one lock pin 76 is insertedthrough a first aperture 78 in housing 80. As shown in FIG. 6, lock pin76 is positioned across at least a portion of the top of tag assembly70, preferably through a second aperture 82 on the opposite side of thehousing. Alternatively, lock pin 76 could extend into the potting of tagassembly 70.

The positioning of the lock pin is not critical, so long as lock pin 78positively secures tag assembly 70 into position within cavity 16 andprevents tag assembly 70 from moving. After insertion through thehousing 14, the lock pin 76 is deformed so that it will not back out ofthe apertures. Tag assembly 70 may then be removed from the housing bysimply drilling lock pin 76 out of aperture 78.

Many different methods of positively locking the tag assembly can beaccomplished. By way of illustration of equivalent locking techniques,instead of a locking pin, a self-tapping screw may be inserted throughaperture 78 and screwed into position within the potting.

In a second embodiment of the present invention, illustrated in FIG. 7,tag assembly 70 has a profile corresponding to that of cavity 16. Tagassembly is assembled into the bottom of cavity 16. Housing 14 extendsabove tag assembly 70 after it has been assembled into cavity 16. Insert90, also having a profile corresponding to cavity 16 is inserted intothe housing until the bottom 96 of insert 90 contacts the top of tagassembly 70, thus securing it in place. Insert 90 is then locked inplace. This may be accomplished by any convenient method, such as byextending a locking pin through insert 90 and deforming it, or byutilizing locking tabs to secure insert 90 to patch assembly 10.However, in the preferred embodiment shown in FIG. 7, insert 90 includesexternal threads 94 which correspond to internal threads 92 formed inhousing 14. Insert 90 is screwed into housing 14 until the insert bottom96 contacts the top of tag assembly 70. Of course, regardless of themethod used to secure tag assembly 70 in place in cavity 16, tagassembly is readily removable for battery replacement or replacement ofthe entire assembly 70 by removing insert 90 from housing 14. It isobvious that tag assembly 70 may be reinserted after accomplishingrepair or replacement, or after retreading of the tire by simplyreplacing insert 90 over the reassembled tag assembly and locking insert90 in place as discussed above.

In a third embodiment of the present invention, FIG. 8, a tag assembly110 including the components previously discussed, is formed withexternal threads 112 in the potting. Rubber patch assembly 120, alsosimilar to rubber patches previously discussed, includes internalthreads 122 formed in housing 124 which mate with the external threads112 of tag assembly. Tag assembly 110 is assembled into rubber patchassembly 120 by simply screwing tag assembly 110 into housing 124. Whilethis arrangement normally should be sufficient to lock tag assembly torubber patch assembly, an optional locking pin or set screw may be addedto the assembly to lock the internal and external threads in place andprevent tag assembly from backing out of the housing of rubber patchassembly 120.

From the foregoing, other embodiments should be obvious. For example, aslot and spline arrangement not shown may be used to lock the tagassembly into the housing. Mating slots and splines are formed in thepotting of the tag assembly and in the housing. After placing the tagassembly into the housing, an optional locking device as previouslydiscussed may be used to prevent the tag assembly from backing out ofthe housing.

In yet another embodiment, depicted in FIG. 9, tag assembly 130 isformed with at least one tab 132, while housing 142 of rubber patch 140is formed with slots 144 corresponding to tabs on tag assembly 130. Atthe bottom of the slots is a ring 146 having an internal diametercorresponding to the slot depth on the housing and extending from eachslot at least partially around the housing bottom. Once tabs 132 of tagassembly 130 are mated with slots 144 of rubber patch and tag assembly130 is inserted into housing 142, tag assembly 130 is rotatedsufficiently so that tabs 132 are rotated into ring 146 and no longerare aligned with slots 144, locking the tag assembly to rubber patch140. An optional locking mechanism, such as discussed previously, may beadded to lock tag assembly 130 to rubber patch 140 if there is a concernabout rotation of tag assembly 130 with respect to rubber patchassembly. Another method of locking tag assembly 130 to rubber patch 140is to insert a piece of material (not shown) into at least one slot 144,for example by an interference fit between the slot and the material, sothat in the event of rotation of the parts with respect to one another,even if the tabs 132 and slots become aligned, tabs 132 are preventedfrom moving axially in the slot. It is obvious that an equivalentstructure can be achieved by reversing the arrangement of slots 144,ring 146 and tabs 132 between tab assembly 130 and housing 142. In thisarrangement, at least one tab is formed in the housing and at least oneslot corresponding to tabs is formed in tab assembly.

While in accordance with the patent statutes, the best mode andpreferred embodiment has been set forth above, the scope of theinvention is not limited thereto, but rather by the scope of theattached claims.

What is claimed is:
 1. In combination: a tire having an innerliner; apatch attached to the innerliner; an electronic monitoring device havingat least one sensor for sensing an engineering condition of a tire; andthe electronic monitoring device being connected to the patch with athreaded connection.
 2. The combination of claim 1, wherein the threadedconnection allows the monitoring device to be removed from the patch. 3.The combination of claim 1, wherein the patch is fabricated from arubber material.
 4. The combination of claim 3, wherein the monitoringdevice is encapsulated with a rigid potting material.
 5. In combination:a tire having an innerliner; a patch attached to the innerliner; thepatch defining a cavity; an electronic monitoring device having at leastone sensor for sensing an engineering condition of the tire; theelectronic monitoring device being at least partially disposed in thecavity of the patch; and the electronic monitoring device beingthreadably connected to the patch.
 6. The combination of claim 5,wherein the electronic monitoring device is disposed entirely within thecavity of the patch.
 7. The combination of claim 5, wherein theconnection between the monitoring device and the patch allows themonitoring device to be removed from the patch.
 8. The combination ofclaim 5, wherein the cavity defined by the patch has a substantiallycircular cross section.
 9. The combination of claim 8, wherein thecavity defined by the patch is substantially cylindrical.
 10. Thecombination of claim 9, wherein the monitoring device is encapsulatedwith a rigid potting material.
 11. The combination of claim 10, whereinthe encapsulated monitoring device is substantially cylindrical.
 12. Incombination: a tire having an innerliner; a patch attached to theinnerliner; the patch being substantially circular in cross section; thepatch defining a cylindrical cavity; a substantially cylindricalencapsulated electronic monitoring device having at least one sensor forsensing an engineering condition of the tire; the cylindrical electronicmonitoring device being substantially disposed in the cylindrical cavityof the patch; and the electronic monitoring device being threadablyconnected to the patch.
 13. The combination of claim 12, wherein thepatch includes a bottom surface and an upper surface; the patch having asidewall that slopes upwardly from the bottom surface to the uppersurface.
 14. The combination of claim 12, wherein the monitoring devicemay be unscrewed from the patch.